Aluminum or copper have been widely used as a material of a wiring conductor for semiconductor devices including ICs (integrated circuits) and VLSIs (very large scaled integrated circuits). However, aluminum, copper, and other typical conductive metals can have very wide conduction bands, e.g., in order of 5 eV, and thus possess a large number of high energy electronic excitations, e.g., excitations with energies far from the Fermi level, which can be detrimental in certain situations in electronic applications.
Therefore, what are needed are conductors with narrow conduction band, which can minimize excited energy deviation.